1. Gaia Commissioning update and flux calibration by Elena Pancino

2. Gaia timeline Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Launch 19 Dec 2013 L2 orbit insertion 1-15 Jan 2014 Commissioning until 18 Jul 2014 EPSL will last 28 days NSL from then on (5 years) Launch 19 Dec 2013 L2 orbit insertion 1-15 Jan 2014 Commissioning until 18 Jul 2014 EPSL will last 28 days NSL from then on (5 years)

3. The Gaia mission All Sky – 10 9 point-like sources – few μas astrometry 6D phase space sampling – SEDs – Astrophysical parameters Focused on Galactic Science – but huge discovery space All Sky – 10 9 point-like sources – few μas astrometry 6D phase space sampling – SEDs – Astrophysical parameters Focused on Galactic Science – but huge discovery space Encased view Two telescopes inside Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

4. All-sky scanning Each object observed 10-250 times (average ≈70-80) Maximum number of passages around ±45° from EP Each object observed 10-250 times (average ≈70-80) Maximum number of passages around ±45° from EP Nominal Scanning Law Sky Coverage Map Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

5. Astrometry principle 1. Object matching in successive scans 2. Attitude and calibrations are updated 3. Objects positions etc. are solved 4. Higher terms are solved 5. More scans are added 6. System is iterated (Global Iterative Solution - GIS) 1. Object matching in successive scans 2. Attitude and calibrations are updated 3. Objects positions etc. are solved 4. Higher terms are solved 5. More scans are added 6. System is iterated (Global Iterative Solution - GIS) Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

6. To give you the feeling… Distance to the Pleiades attainable by Gaia: tiny errorbars and a large sample of stars Each plotted star will also have a radial velocity, magnitude, color, and astrophysical parameters by means of high-resolution spectroscopy in the CaT region Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

7. Science possibilities Focus on the Milky Way Solar system objects Distant galaxies and QSO Fundamental physics Transients & variables Distance scale Focus on the Milky Way Solar system objects Distant galaxies and QSO Fundamental physics Transients & variables Distance scale Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

8. Focal plane & instruments Sky mappers (SM) Astrometric field (AF) Sky mappers (SM) Astrometric field (AF) Spectro-photometers (BP & RP) Radial velocity spectrometer (RVS) Spectro-photometers (BP & RP) Radial velocity spectrometer (RVS) Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

9. Sky Mappers & object detection Bright stars (V<13 mag) Intermediate stars (13 <V<16 mag) squares for Gaia spin rate measurements Faint stars (16<V<20 mag) 1D profile only Each detected object is assigned a 2D window Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

10. Astrometric field First images: Sadalmelik (α Aqr) Telescope not aligned nor focused then White light (G-band ≈ V band) Photometry and astrometry Astrometric performance (G2V) 3<V<12 mag: 5-14 μas V=15 mag: 24 μas V=20 mag: 540 μas NGC 2516, commissioning image Later 1 star = 1 little window White light (G-band ≈ V band) Photometry and astrometry Astrometric performance (G2V) 3<V<12 mag: 5-14 μas V=15 mag: 24 μas V=20 mag: 540 μas NGC 2516, commissioning image Later 1 star = 1 little window Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

11. Tuning Gaia First images: Cat’s eye nebula before and after spin rate adjustment This might be one of the last images – Gaia is not an imaging mission! First images: Cat’s eye nebula before and after spin rate adjustment This might be one of the last images – Gaia is not an imaging mission! Spin rate adjustment (Telescope focus & alignment) Courtesy of SOC calibration team Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

12. BP/RP dispersed images First images: NGC 1818 in the LMC 2.85 sec integration, 212 x 212 arcsec 2 Blue and red channels R≈100 dispersed images Color-correction for AF SEDs for: Classification Parametrization Blue and red channels R≈100 dispersed images Color-correction for AF SEDs for: Classification Parametrization Courtesy of Jordi & Carrasco Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

13. Gaia integrated magnitudes Four bands (G, BP, RP, RVS) Four integrated magnitudes One important colour (G BP -G RP ) Four bands (G, BP, RP, RVS) Four integrated magnitudes One important colour (G BP -G RP ) G band performance (G2V) V=15 mag, 1 mmag V=18 mag, 2 mmag V=20 mag, 6 mmag BP performance (G2V) V=15 mag, 4 mmag V=18 mag, 13 mmag V=20 mag, 80 mmag RP performance (G2V) V=15 mag, 4 mmag V=18 mag, 11 mmag V=20 mag, 59 mmag G band performance (G2V) V=15 mag, 1 mmag V=18 mag, 2 mmag V=20 mag, 6 mmag BP performance (G2V) V=15 mag, 4 mmag V=18 mag, 13 mmag V=20 mag, 80 mmag RP performance (G2V) V=15 mag, 4 mmag V=18 mag, 11 mmag V=20 mag, 59 mmag Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

14. RVS spectra First spectra: the bright star HIP 86564 Courtesy of Katz, Marchal, & Soubiran Pre-launch simulations R≈10000 CaT spectra Down to V ≈ 16.5 mag Full object parametrization Chemical abundances RVS performances (GV2) V=12 mag, 1 km/s V=15 mag, 15 km/s R≈10000 CaT spectra Down to V ≈ 16.5 mag Full object parametrization Chemical abundances RVS performances (GV2) V=12 mag, 1 km/s V=15 mag, 15 km/s Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

15. Second part: Commissioning update

16. (1) Gaia brightness Gaia seen by ESO-VST, image courtesy ESO Optical tracking necessary for attaining max performance Gaia is 3 mags fainter than expected (V≈20.5 mag) The GBOT group negotiated time at 2-4m telescopes Optical tracking necessary for attaining max performance Gaia is 3 mags fainter than expected (V≈20.5 mag) The GBOT group negotiated time at 2-4m telescopes Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

17. (2) L2 environment Micro-meteoroid hit, courtesy van Leeuwen Large hits ok, small hits orders of mag more frequent than expected Attitude control system copes very well with this dusty environment Attitude modeling more complex – some noise at bright end Large hits ok, small hits orders of mag more frequent than expected Attitude control system copes very well with this dusty environment Attitude modeling more complex – some noise at bright end Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

18. (3) Stray light SAA = 45° (nominal operation angle) SAA = 0° (commissioning maneuver) Sun light dominates night sky dominates Higher than expected backround levels, varying with time Caused by scattered sunlight, affecting mostly faint sources The solution is a redesign of the background treatment software Higher than expected backround levels, varying with time Caused by scattered sunlight, affecting mostly faint sources The solution is a redesign of the background treatment software Figures by Davidson Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

19. (4) Contamination 1 st decontamination 2 nd decontamination Response loss (water ice) – heating to decontaminate Unintended outgassing path from service to payload module Response loss (water ice) – heating to decontaminate Unintended outgassing path from service to payload module Figure by Fabricius Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

20. (5) BAM variations The BAM measures 6h variations - some are confirmed – open issue BAM measurements 1 day astro solution Figure by First Look Team Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

21. Gaia status summary Five unexpected issues emerged after commissioning Two are minor (GBOT and L2 dust) Three have an impact on Gaia performances Stray light, contamination, BAM variations Excellent maneuvers from launch to L2 orbit insertion We have a good propellant reservoir for the future Some minor micro-thruster problems Service module commissioning ok The downlink allows for high data rate The rubidium clock and GB phased array antennaes are ok Payload module works well (Electronics, CCDs, optics) Gaia -> ESOC -> DPAC chain working excellently so far Five unexpected issues emerged after commissioning Two are minor (GBOT and L2 dust) Three have an impact on Gaia performances Stray light, contamination, BAM variations Excellent maneuvers from launch to L2 orbit insertion We have a good propellant reservoir for the future Some minor micro-thruster problems Service module commissioning ok The downlink allows for high data rate The rubidium clock and GB phased array antennaes are ok Payload module works well (Electronics, CCDs, optics) Gaia -> ESOC -> DPAC chain working excellently so far Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

22. Third part: Flux calibration

23. Gaia flux calibration Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory On-board pre-processing Ground processing Internal Calibration (internal standards) External Calibration (external standards)

24. External calibration model Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia obs SED Instrument LSF Sample Wavelength In matricial form: S obs = D x S true S true = D -1 x S obs Two problems: Matrix is rectangular Stars ≠ orthogonal set You need many (200) stars of different spectral types with <1% calibration wrt Vega In matricial form: S obs = D x S true S true = D -1 x S obs Two problems: Matrix is rectangular Stars ≠ orthogonal set You need many (200) stars of different spectral types with <1% calibration wrt Vega

25. SPSS observing campaign Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory 450 nights at 6 telescopes, started in 2006 (end 2015) Four campaigns Spectroscopy (R≈2000) Absolute photometry Constancy monitoring (>10 mmag) Short term (2 h) Long term (3 yrs) 215 remaining candidates From CALSPEC & literature One CALSPEC variable found Preliminary results published (Pancino et al., 2012) 450 nights at 6 telescopes, started in 2006 (end 2015) Four campaigns Spectroscopy (R≈2000) Absolute photometry Constancy monitoring (>10 mmag) Short term (2 h) Long term (3 yrs) 215 remaining candidates From CALSPEC & literature One CALSPEC variable found Preliminary results published (Pancino et al., 2012) BFOSC@Cassini, Loiano EFOSC2@NTT, La Silla LaRuca@1.5m, San Pedro Martir ROSS@REM, La Silla Dolores@TNG, La Palma CAFOS@2.2m, Calar Alto

26. Data analysis Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory

27. The pre-launch (internal) release Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory October 2013 94 SPSS Photometric sky Pipeline testing Quality <1% central Red: fringing (10%) Blue: noisy (3-5%) To do for borders 330-1050 nm More S/N Models extension October 2013 94 SPSS Photometric sky Pipeline testing Quality <1% central Red: fringing (10%) Blue: noisy (3-5%) To do for borders 330-1050 nm More S/N Models extension

28. Next steps Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory Gaia at HST Calibration Workshop Elena Pancino Baltimore August 2014 INAF- Bologna Observatory First Gaia release expected 2017 – SPSS release in 2016 Will build on the best 94 SPSS increasing their quality Later releases will expand on the number of SPSS as well Data will be available @ ASDC archive (under works) 100000 raw frames + 3000 calibration masterframes First Gaia release expected 2017 – SPSS release in 2016 Will build on the best 94 SPSS increasing their quality Later releases will expand on the number of SPSS as well Data will be available @ ASDC archive (under works) 100000 raw frames + 3000 calibration masterframes

29. That’s all, Thank you!